Honeywell Precision Pressure Transducer 2
PPT2 User’s Manual
ADS-14221, PPT2 User Manual
October, 2016
ADS-14221 Rev. 10/16
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No part of this manual may be reproduced or transmitted in any form or by any means, electronic or mechanical,
including photocopying and recording, for any purpose, without the express written permission of Honeywell, Inc.
Honeywell reserves the right to make changes to any products or technology herein to improve reliability,
function or design. Honeywell does not assume any liability arising out of the application or use of any product
or circuit described herein; neither does it convey any license under its patent rights nor the rights of others.
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Table of Contents
Table of Contents ................................................................................................. 3
1.0 Product Overview .......................................................................................... 4
2.0 Getting Started .............................................................................................. 5
3.0 PPT2 Command Summary ........................................................................... 9
4.0 Terminology ................................................................................................ 17
5.0 Command Descriptions (alphabetical order) ............................................... 21
6.0 Electrical Connections ................................................................................ 75
7.0 Installation Recommendations, Cautions and Materials of Construction .... 77
8.0 Firmware Errata .......................................................................................... 79
Appendix A: PPT2 Binary Command Format for P3 and P4 Commands: .......... 80
Appendix B: ASCII Table .................................................................................... 83
Appendix C: Setting an Analog Pressure Set Point ............................................ 84
Appendix D: RAM Initialization ........................................................................... 85
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1.0 Product Overview
The Honeywell Model PPT2 Precision Pressure Transducers provide high accuracy pressure readings in both
digital and analog form. The first-time user will be able to use the PPT2 within minutes, yet capability exists to
configure the PPT2 to optimize performance in the User’s specific applications. Throughout this User’s Manual,
the PPT2 may be referred to as Precision Pressure Transducer.
The heart of the PPT2 measuring system is a silicon piezoresistive sensor which contains both pressure and
temperature-sensitive elements. Digital signals representing temperature and pressure are processed by the
PPT2 microprocessor to produce calibrated, temperature-compensated pressure readings over the entire
operating temperature and pressure range.
Both the analog and digital outputs are internally corrected over the full operating range. The PPT2 has a digital
accuracy of 0.075% of full scale (FS). Note that full scale for a 20 psig and a 20 psia is 20 psi, but for a 20 psid it
is 40 psi, the sum of + Full scale and – Full Scale. This is important to note when determining the accuracy
allowance.
The PPT2 receives commands and sends digital data using either an RS-232 serial port or a multi-drop RS-485
serial port of a computer. (Note: many newer computers will have only USB ports, no RS-232 or RS-485 ports. A
USB converter can be used to provide the required RS-232 or RS-485 port.)
Using the RS-232 type PPT2, up to 89 units can be connected in a ring configuration to a single serial port of a
computer. The RS-485 type PPT2 allows up to 89 PPT2’s to be connected to a two-wire multi-drop bus. Group
(multicast) addressing allows up to nine groups of PPT2’s to be addressed with a single command. Global
(broadcast) addressing will send a command to all PPT2’s on the serial bus.
Any computer having a serial port and terminal emulation software can be connected to the PPT2 to allow the
user to set baud rates, reading rates, reading resolution, units of pressure and other choices. (User modified
functions must be set through the digital interface, using a computer with a serial port). The user-modified
functions may either be used temporarily, until the PPT2 is powered down, or may be stored in the PPT2 internal
EEPROM to automatically configure the PPT2 each time power is applied.
Analog output from the PPT2 16-bit digital-to-analog converter may be obtained without a host computer.
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2.0 Getting Started
2.1
OVERVIEW
The first-time user should approach the PPT2 in a manner analogous to using a word processor program; i.e.,
many features are available but one may begin by using only those of interest at the moment.
As shipped from the factory, the default settings provide a pressure transducer that will be usable for many
applications. Once the user is familiar with the performance and command structure, changes may be made and
stored using the ‘Store Parameters’ (SP) command. Once stored, the user-defined settings are activated each
time the PPT2 is powered up. This tailors the performance of the PPT2 to meet the needs of a particular
application.
2.2
EQUIPMENT NEEDED
To prepare the PPT2 for operation, three items are needed:
• A mating connector with proper wiring connections (see connector part number and wiring diagrams in
Section 6);
• A DC power supply;
• A source of pressure that is properly matched to the range and type of the PPT.
To operate the PPT2 in the analog output mode, one additional item is needed:
•
Voltage Output
- A five digit voltmeter with 0-5 volt range connected between Analog Out and Signal
Common. A computer is not required to read the Analog output.
To operate the PPT2 in the digital output mode, one additional item is needed:
• A computer, or host processor, having an RS-232 or RS-485 serial port (or suitable USB adapter) and
terminal emulation program.
The wiring diagram designates which PPT2 pins must connect to the computer “send”, “receive” and
“common” pins for proper communications.
2.3
TERMINAL PROGRAM SETTINGS
Enter the following settings in the terminal program:
Baud Rate:
Start Bits:
Data Bits:
Stop Bits:
Parity:
9600
1
8
1
None
Attach a line feed to the carriage return.
Turn the local echo ON.
When shipped from the factory, the PPT2 is set to a baud rate of 9600, 1 start bit, 8 data bits with no parity and 1
stop bit. If the baud rate has been subsequently changed, and is unknown, it will be necessary to search all baud
rate values to reestablish communication. See the BP command description in Section 5 of this manual for
possible settings.
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嵌入式系统
